Application installation is unavailable because another operation is running: Plugin Activation for Issue - When trying to install the plugin, it was showing the following message: - This message appeared for a very long time.Cause- The customer closed the plugin activation window before activation was complete. - Due to a cache issue, it was showing the plugin activation is still in progress even though the plugin activation completed. ResolutionAfter clearing the cache[cache.do], the plugin activation completed and other plugins are installing successfully.